In settling tanks for the removal of solids from liquids such as cuttings in coolants, often large objects are accidentally or otherwise dropped into the open settling tanks which often cause jamming of their drag-out conveyors employed for removal of the settlings from these tanks. Furthermore, it is rarely possible to see through the liquid in these tanks to determine what actually caused the jamming of their conveyors. Thus, it was necessary to drain the tank to repair the conveyor and remove the object that caused its damage, all of which causes much loss of time and is very expensive.
Although spring-urged idler sprockets for drag-out conveyors have been employed at the bottom of ramps or inclined sides of receptacles, their compression has never been controlled and indicated above the surface of the material in the receptacles or arranged to be free from being contaminated by the material in he receptacle.
Furthermore, no means known has ever been employed to sense the drag on the conveyor along the bottom of the tank only without sensing the drag up the ramp of the conveyor, which sensing can also be employed for controlling the amount of settlings remaining on the bottom of the tank, particularly if a filter is placed in the bottom of the tank which requires a predetermined thickness of settlings thereon.